Leveling while solo?

[Shad]

There is one more way.
Aim for most melee or (cross)bow damage and go for mobs that give at least 5-10 xp and could be killed in no more then 1-2 rounds. That way one would not struggle and risk killed, get tons of low-level loot (have to be able to haul tons), and build up for better gear.

If there is a melee-type on the surface, I'd go like this (adoptable to other types too):
(There would be lots of text with words like lvl req EB etc. under spoiler.)

Hidden: show

Level 1-2: Quests
You got 1000 and your clothes.
Quests get you to level 2.
Get FullPlate (lvl req 2, cost around 1000)
Get biggest stick (two-handed, most base damage) - best if +1 attack ( not EB because level req). You get damage from str and base dmg, you have to ensure you hit before you got hit much). Greataxe, warmace, halberd etc.
Go to BG Graveyard (RIP)

Level 2-5(7): BG Graveyard
Grind deadlings.
Lvl 5 is time to get familiar with merchants, upgrade gear (5 is req for 2 ac items, 3 attack weapon, 6 is lvl req for Fullplate +2). Better you have no xp over 5 to loose in travel.
Best it is evening and no less then 2 hours til reset - chance to find good items sold by adventurers to merchants.
Go south ( ). Visit FAI (merchant) then Candlekeep (2 good merchants) then Beregost (2+ merchants, Maltz's quest) then Nashkel (at least 1 good merchant, Hunter's quest).
Careful on the way back - you'll have up to 1000 xp with you from Hunter's quest but you are already familiar with roads.
Better prices at auction (FAI and Palace District has the same items) but no guaranty there is what you need.
Get +2ac boots, amulet and deflection item. Best not to go for +2 deflection cloak because you'll soon need that slot for Regen cloak.
Look for +2 str item (usually gloves, Candlekeep if remember right have it)

Regen cloak's almost mandatory at the lowest level you can wear one (7). Save for it.

Return to BG.
Til lvl 7... grind deadlings.

Go for regen cloak (there are many variants of these, some of them are lvl8, but you can easily go for 7). Seven Sons in the Palace District.
Lvl 7 is aslo req for +2 EB weapon. Time to get it too - it surfaces sometimes dead cheap at Auction.
Now you have some weapon focuses probably, so get your favorite. Best it is a big one stick, its reliable.

Look for +2-3 will save items. +3 save item (if not ring it would be lvl4 req but you'll only need it now), get other items which can improve your saves, You'll soon need it.
Lvl 7 is enough for +3 AC amulet and boots but these are costly.
Candlekeep have +2 saves rings (merchant in small house).

Go to Gibberling caverns.

Lvl 7-10: Gibberling caverns.
I like it more then Kobold ruins. More xp, less doors, comfy rooms, lil boss. Just need will to perform good.
Write me to sell Gibberling hearts, 300 gold per each.
Or eat them, if your character would do such thing.
Lvl 8 is time for +3 Fullplate.
Sometimes amulet with 5% magical immunity surfaces at auction, you may want to have it, if you haven't got +3ac one.
Get best +3eb (lvl 10) stick you can - dead cheap at Auction, and look for +4 EB one (lvl 12).
Go to Gnoll caverns near the road to Candlekeep.

Lvl 10-14(15-16):
Grind gnolls.
Its great compound but apparently first level is the best and most comfy thing for grinding.
Check crates and chests, I once got mithral FP there.
Use switch to magic immunity amulet if got troubles with Occultist (it will shrug off 1 pint of dmg of every magic missile) - most do get them, and kill occultists fast. If you meet 3 or more in one place - Run!

Look for Reflex gear.
Look for vampiric regen weapons.

Look out for Xvarts party (lvl 12+ and mob of friends, if no friends then Gnolls are better) or Giants (14+, good reflex, evasion or damage reduction) party.

Giants go til lvl 22 (non ECL).

Anyway, look at it as on fallback plan. Anytime you see adventurin' party you can fit in - go for it!

[thids]

Why would you do quests at level 1? Regardless of the build, just pick up a heavy shield (if proficient), a sling and a bunch of bullets and go to the graveyard. Grind out level 4 and then do city quests before hitting hilltop.

[Shad]

There is lots of ways to get it, but fighter types does more dps in melee, and more dps equals more xp. In fp its comfy, and fp req level 2:) Though it may be not worth time to do city quests at all but farmlands quests, and get level 2 with sling - why not.
xp per hour at lvl 4-5 at graveyard would still be better then in hilltop, if one's soloing and not monk with flurry. And when one gets second attack, +2 ac items and a bit of will, hilltop is worthless because gibberlings give better xp, and hearts.